Environmental issues have, in the past twenty years, evolved in importance. Environmental issues that were once sideline issues are now at the forefront of public thought and policy. Especially important are issues related to disposal of waste and the rapidly dwindling available landfill space. An ever-increasing population and the concomitant increase in consumer waste production, coupled with ever-dwindling landfill space, has fueled the search for alternatives to waste disposal methods.
One attractive way of reducing the amount of solid waste being disposed into the environment is the reclamation of reusable raw materials from disposable waste. Efforts to reclaim these raw materials have expanded recently to the point where they have become a profitable enterprise. The increased business incentive to recycle, and the public's perception that recycling works, and that it is not just a worthy cause but a necessary one, has driven the recycling industry to new heights.
The reclamation of single-use human waste collecting and/or absorbing products (disposable diapers) is one way of reducing the amount of solid waste being "dumped" into the environment. Disposable diapers currently take up approximately 2-3 percent of landfill volume. Moreover, human biological waste from disposable diapers is a potentially virulent contaminant of underwater aquifers and rivers. Awareness of the eventual health hazards and the increasing concern for the environment has generated a desire to do away with the accepted practice of using a diaper once and throwing it away.
In the past, before disposable diapers became popular, reusable cloth diapers were commonly used. Cloth diapers were washed and reused to ensure that the waste products ended up in a sewage treatment plant to substantially neutralize any harmful bio-organisms. However, the sheer numbers of diapers used during an infant's development made washing them a distasteful task. In addition, diaper covers or wraps used to fasten the diapers required washing. Also, the ends of cloth diapers were often affixed together with safety pins, which tend to be sharp and difficult to manipulate. Finally, cloth diapers were not as absorbent as disposable diapers which use special high-absorbent materials. The ease and convenience of disposable diapers has, therefore, become a more attractive alternative to cloth diapers. In fact, nearly 80-90% of all diapers currently used in America are disposable diapers.
The solution contemplated by the present invention provides the convenience of using disposable diapers with the environmental advantages of using reusable cloth diapers. Just as with bottles, cans, plastics and newspapers, curbside collection of soiled disposable diapers could be instituted to make the prospect of recycling such diapers minimally intrusive to consumers. However, the nature of the construction of disposable diapers makes their recycling problematic.
Disposable diapers are generally comprised of an absorbent pulp-like filler material made of wood or corn, with super-absorbent gel-like chemical beads called acrelites interspersed throughout. The pulp is held in place within the diaper by an outer plastic liner, and an inner plastic liner. Various adhesives are also used to join the plastics together. Plastic tabs are used to facilitate taping of the diaper onto the infant. The current difficulty in recycling soiled disposable diapers is that the diaper materials must be separated and cleaned before the raw materials can be utilized. Separation of the raw materials is required because only the separate raw materials can be sold and utilized properly. Unfortunately, means for efficiently separating the various materials which make up a disposable diaper are not well-known, and currently only a few attempts have been made to provide such technology.
Previously, methods for separating paper and plastic from disposable diapers have been based on generating enough heat to destroy the bonding of the adhesives which bind the plastic materials. In U.S. Pat. No. 4,990,244, a process and apparatus for separating plastic and absorbent materials from diapers is shown in which the adhesives joining the layers of plastic together are dissolved by raising the temperature of the adhesives in hot water. The hot water acts to dissolve the adhesives to allow the plastic and absorbent material to be separated.
The inherent problem in this method is that it requires a supply of hot water which in turn requires energy to produce. In the recycling industry, profit margins are relatively low and additional expenses for heating and maintaining hot water to successfully break down the adhesives can be a significant financial burden. Moreover, the separation of the two main diaper components is dependent on the complete liquidization of the joining adhesives. This liquidization will occur only at a certain temperature which then must be sustained while the adhesives are being washed away. Any residual adhesive will disadvantageously hinder the complete separation of plastic and absorbent material and/or may remain as an unwanted residue on the by-products. Consequently, there is a need for a more effective and cost-efficient means for reclaiming the primary components from soiled diapers and the like.
Another inherent difficultly in recycling the raw material components of a disposable diaper is that the diapers must be washed, cleaned, and then dehydrated so that the raw materials can be properly packaged and sold. Though the washing process has not presented much difficulty, very little technology previously has been developed to remove the excess water and moisture from the pulp-like material once it has been washed. Consequently, there is a need for an efficient and cost-effective method of removing water, and consequently the excess weight, from the pulp-like material.
Additionally, due to the relatively slim profit margins generated by a typical recycling enterprise, a cost effective means for the overall recycling process for disposable diapers must be provided.